(BRUNSWICK, Ga.) — One of the rescuers who helped get four crew members out of the Golden Ray, the cargo ship that capsized and caught fire off the coast of Georgia on Sunday, described the harrowing attempt to free the trapped men.

Sean Cogan, a rope access supervisor for Elevated Safety, a company that trains and helps people rappel on ropes, was appointed the rescue team leader for salvage company Defiant Marine, he told ABC News.

Cogan, who typically helps engineers get to hard-to-access places like bridges for inspection, was part of the team that first heard tapping noises coming from the Golden Ray as they rappelled over the side of the ship.

He knew “the clock was ticking” for the men as soon as he got to St. Simons Sound, off the coast of Brunswick, Georgia, he said.

The first priority was to drill a small hole big enough to shake the men’s hands, hand them bottles of water, flashlights and a device to communicate on and assure them that help was on the way, Cogan said.

It was about 120 degrees where rescue teams were working outside the ship and even hotter inside, Coast Guard Capt. John Reed told reporters on Monday.

Once teams drilled the first half-inch hole to get an air monitor and airflow into the ship, Cogan could feel the hot air spilling from inside, he said, adding that it felt like they were drilling into a thermal oven.

“With each hole, I think it just got more and more, in terms of intensified focus, of, ‘We’ve got to finish this,'” he said.

Three of the crew members trapped inside were grouped together, while the fourth was trapped behind a glass enclosure in the engineering room, Reed said.

They could hear each other, but could not access each other, Cogan said, adding that the “first thing” the three shipmates asked for was a set of tools so they could help free him, Cogan said.

“Those guys that were in that ship are probably the strongest in terms of mental fortitude of anything I’ve seen,” he said.

Once a larger hole was drilled, the first two crew members were able to climb out with little assistance, but Cogan and others had to go in and help the third, he said. At that point, the crew had been stuck inside the ship for nearly 34 hours.

Cogan said the wrecked vessel was not a “pleasant environment to be in.” Everything inside had shifted, and the ship had been “baking” under the sun.

Cogan described the moment after they recovered the fourth crew member as “very emotional.”

“I mean, to see two arms, two legs and a smile coming up the ladder at you, that’s a surprise,” he said.

It is unclear what caused the ship, which was carrying vehicles on its way to Baltimore, to catch fire and list on its side.

The operation has now transitioned to salvage and mitigating any possible pollution, Coast Guard officials said at a press conference Tuesday.

The Port of Brunswick, one of the busiest in the nation, remains closed, but the Coast Guard hopes to open it to limited commercial traffic by Thursday, officials said.